-
border.color
: color
-
border.width
: int
-
color
: color
-
path
: list<coordinate>
Methods
-
void
addCoordinate
(
coordinate
)
-
void
removeCoordinate
(
coordinate
)
Detailed Description
The MapPolygon type displays a polygon on a Map, specified in terms of an ordered list of
coordinates
. For best appearance and results, polygons should be simple (not self-intersecting).
The
coordinates
on the path cannot be directly changed after being added to the Polygon. Instead, copy the
path
into a var, modify the copy and reassign the copy back to the
path
.
var path
=
mapPolygon
.
path;
path
[
0
]
.
latitude
=
5
;
mapPolygon
.
path
=
path;
Coordinates can also be added and removed at any time using the
addCoordinate
and
removeCoordinate
methods.
For drawing rectangles with "straight" edges (same latitude across one edge, same latitude across the other), the
MapRectangle
type provides a simpler, two-point API.
By default, the polygon is displayed as a 1 pixel black border with no fill. To change its appearance, use the
color
,
border.color
and
border.width
properties.
Note:
Since MapPolygons are geographic items, dragging a MapPolygon (through the use of
MouseArea
) causes its vertices to be recalculated in the geographic coordinate space. The edges retain the same geographic lengths (latitude and longitude differences between the vertices), but they remain straight. Apparent stretching of the item occurs when dragged to a different latitude.
MapPolygons have a rendering cost that is O(n) with respect to the number of vertices. This means that the per frame cost of having a Polygon on the Map grows in direct proportion to the number of points on the Polygon. There is an additional triangulation cost (approximately O(n log n)) which is currently paid with each frame, but in future may be paid only upon adding or removing points.
Like the other map objects, MapPolygon is normally drawn without a smooth appearance. Setting the
opacity
property will force the object to be blended, which decreases performance considerably depending on the hardware in use.
Example Usage
The following snippet shows a MapPolygon being used to display a triangle, with three vertices near Brisbane, Australia. The triangle is filled in green, with a 1 pixel black border.
Map {
MapPolygon {
color:
'green'
path:
[
{ latitude:
-
27
,
longitude:
153.0
}
,
{ latitude:
-
27
,
longitude:
154.1
}
,
{ latitude:
-
28
,
longitude:
153.5
}
Property Documentation
autoFadeIn
:
bool
This property holds whether the item automatically fades in when zooming into the map starting from very low zoom levels. By default this is
true
. Setting this property to
false
causes the map item to always have the opacity specified with the
QtQuick::Item::opacity
property, which is 1.0 by default.
This property was introduced in Qt 5.14.
backend
:
MapPolygon
.
Backend
This property holds which backend is in use to render the map item. Valid values are
MapPolygon.Software
and
MapPolygon
.OpenGL
. The default value is
MapPolygon
.Software
.
Note:
The release of this API with Qt 5.15 is a Technology Preview
. Ideally, as the OpenGL backends for map items mature, there will be no more need to also offer the legacy software-projection backend. So this property will likely disappear at some later point. To select OpenGL-accelerated item backends without using this property, it is also possible to set the environment variable
QTLOCATION_OPENGL_ITEMS
to
1
. Also note that all current OpenGL backends won't work as expected when enabling layers on the individual item, or when running on OpenGL core profiles greater than 2.x.
This property was introduced in Qt 5.15.
border.width
:
int
This property is part of the border property group. The border property group holds the width and color used to draw the border of the polygon.
The width is in pixels and is independent of the zoom level of the map.
The default values correspond to a black border with a width of 1 pixel. For no line, use a width of 0 or a transparent color.
path
:
list
<
coordinate
>
